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Open Access Nano Express

Unusual surface and edge morphologies, sp 2 to sp 3 hybridized transformation and electronic damage after Ar+ ion irradiation of few-layer graphene surfaces

Salim Hamood Al-Harthi1*, Mohammed Elzain1, Muataz Al-Barwani1, Amal Kora'a1, Thomas Hysen2, Myo Tay Zar Myint3 and Maliemadom Ramaswamy Anantharaman2

Author Affiliations

1 Physics Department, College of Science, Sultan Qaboos University, P.O. Box 36, Al Khoud, Sultan Qaboos, Muscat, 123, Oman

2 Department of Physics, Cochin University of Science and Technology, Cochin-22, Kochi, Kerala, 682 022, India

3 Center of Excellence in Nanotechnology, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani, 12120, Thailand

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Nanoscale Research Letters 2012, 7:466  doi:10.1186/1556-276X-7-466

Published: 19 August 2012

Abstract

Roughness and defects induced on few-layer graphene (FLG) irradiated by Ar+ ions at different energies were investigated using X-ray photoemission spectroscopy (XPS) and atomic force microscopy techniques. The results provide direct experimental evidence of ripple formation, sp2 to sp3 hybridized carbon transformation, electronic damage, Ar+ implantation, unusual defects and edge reconstructions in FLG, which depend on the irradiation energy. In addition, shadowing effects similar to those found in oblique-angle growth of thin films were seen. Reliable quantification of the transition from the sp2-bonding to sp3-hybridized state as a result of Ar+ ion irradiation is achieved from the deconvolution of the XPS C (1s) peak. Although the ion irradiation effect is demonstrated through the shape of the derivative of the Auger transition C KVV spectra, we show that the D parameter values obtained from these spectra which are normally used in the literature fail to account for the sp2 to sp3 hybridization transition. In contrast to what is known, it is revealed that using ion irradiation at large FLG sample tilt angles can lead to edge reconstructions. Furthermore, FLG irradiation by low energy of 0.25 keV can be a plausible way of peeling graphene layers without the need of Joule heating reported previously.

Keywords:
Few layer graphene; Argon sputtering; Electronic damage; Edge reconstructions